Rare prostate cancer subtypes demand better detection and dedicated trials

A comprehensive review published in Nature Reviews Urology argues that rare histological forms of prostate cancer, which together account for less than 5% of all prostate cancers, remain dangerously under-recognized. The article, authored by an international team of urologic oncologists and pathologists, covers mucinous adenocarcinoma, intraductal carcinoma, ductal adenocarcinoma, neuroendocrine prostate cancer including treatment-emergent small-cell neuroendocrine carcinoma, sarcomatoid carcinoma and basal cell carcinoma. Each of these entities differs morphologically, molecularly and clinically from acinar adenocarcinoma, the histological type that accounts for the vast majority of cases and on which most screening, diagnostic and treatment standards are built.

One of the review's central points is that the apparent rarity of these subtypes may partly be an artifact of clinical practice rather than a reflection of biology. Many treatment-emergent phenotypes are seldom encountered in routine care because metastatic biopsies are infrequently performed, meaning that tumors that transform into aggressive histologies under the pressure of androgen-receptor-directed therapy can go undetected. The authors suggest that sampling limitations have contributed to a distorted picture of how often these variants actually arise, particularly in patients with advanced disease.

Clinically, the rare histologies tend to behave aggressively. The review describes atypical metastatic patterns and reduced responsiveness to conventional therapies, and notes that limited retrospective data suggest worse outcomes for patients with a rare histology compared with those who have typical acinar adenocarcinoma. Because these tumors often do not follow the natural history familiar to clinicians managing common prostate cancer, delays in recognition can translate into diagnosis at advanced stages.

Screening itself is part of the problem. As a result, these cancers can evade the standard diagnostic pathway and present only when they have already spread. The authors underscore the importance of imaging, pathology expertise and molecular profiling in closing this detection gap.

On the diagnostic side, the review identifies multiparametric MRI, immunohistochemistry and genomic profiling as crucial tools for accurate recognition and risk stratification. Histopathological assessment remains the foundation of subtype identification, but the authors describe an integrated workflow in which imaging and molecular characterization complement morphology. Genomics offers some of the most concrete therapeutic leads described in the review.

Histological type-specific genomic alterations, including DNA repair deficiencies, loss of the tumor suppressors RB1 and TP53, and mismatch repair mutations, are enriched in selected subtypes. The review frames these findings as opportunities, noting that treatment recommendations for the rare histologies are still largely extrapolated from acinar adenocarcinoma rather than established by direct evidence. The evidence base itself is thin.

The authors report that prospective trials and guideline-level evidence specific to the rare subtypes remain scarce, and that these entities are under-represented in standard guidelines and clinical trials. This means that patients with ductal, mucinous, intraductal, neuroendocrine or sarcomatoid carcinomas are frequently treated according to protocols designed for a different disease. To address these gaps, the review calls for improved diagnostic precision, integration of germline and somatic testing, and collaborative prospective registries.

The authors argue that systematic collection of data on patients with rare histologies is essential to optimize clinical management and advance precision medicine for this population. The overall message is that rare prostate cancer histologies are an under-recognized source of morbidity and mortality. The authors position better recognition, molecular profiling and coordinated data collection as the essential ingredients for developing evidence-based strategies for a group of cancers that, despite their collective clinical importance, have long been managed in the shadow of a more common disease.

Subject of Research: Rare histological subtypes of prostate cancer and their detection, characteristics and treatment

Article Title: Rare prostate cancer histologies: detection, characteristics and treatment

Article References: Melão, B. V. L. A., Jardim, D. L., Li, R., Collins, K., Agarwal, N., Grivas, P., Briganti, A., Necchi, A., Cheng, L., & Spiess, P. E. (2026). Rare prostate cancer histologies: detection, characteristics and treatment. Nature Reviews Urology. https://doi.org/10.1038/s41585-026-01194-z

Image Credits: AI Generated

DOI: 10.1038/s41585-026-01194-z

Keywords: prostate cancer, rare histologies, neuroendocrine prostate cancer, ductal adenocarcinoma, intraductal carcinoma, PSA screening, genomic profiling, DNA repair deficiency, TP53, RB1, molecular diagnostics, clinical trials